An interface device that includes a projector combined with a camera has been developed in recent years. Such an interface device captures a content of operation, by using a camera, performed by a user on an image projected from a projector, recognizes the content of operation on image data, and thereby achieves an interactive operation. PTL 1 discloses an interface device including a projector combined with a camera.
The interface device in PTL 1 includes an irradiation means that uses a phase-modulating spatial light modulation element. The interface device in PTL 1 forms a desired image on a projection surface by causing a phase distribution for forming the image to be displayed on a display surface of the spatial light modulation element and projecting light reflected from the display surface irradiated with light onto the display surface.
A projection image by a projector that uses a phase-modulating modulation element has several problems in terms of image quality. One of the problems is a ghost image (hereinafter referred to as a ghost) that appears in association with a desired image.
FIG. 25 illustrates an example in which a viewing image 100 is displayed on a projection surface by using projection light from a projector that uses a phase-modulating modulation element. The viewing image 100 includes an up-pointing arrow as desired display information 100D. Then, a first-order ghost 100G appears in a position in which the display information 100D is located when being rotated 180 degrees about a center point 100C (which is not displayed in reality) of the viewing image 100. Note that while a higher-order ghost also appears in a position at a distance of an integer multiple of a distance from the center point 100C of the viewing image 100 to the display information 100D, the higher-order ghost is omitted from FIG. 25. Appearance of the ghost 100G varies depending on performance of the phase modulation element, a definition of gamma transformation, temperature, and the like.
The ghost 100G is visually recognized when brightness thereof becomes about several percent of brightness of the display information 100D. Therefore, a technique for removing a ghost from a visually recognized image is demanded.
PTL 2 discloses a depth-of-field expanding system that is capable of removing a ghost and acquiring an image with an expanded depth of field. The system in PTL 2 rotates a pupil modulation element which performs modulation of a phase distribution on light from a subject, removes a ghost by using an intermediate image acquired as a result of the rotation, and acquires an image with an expanded depth of field.
PTL 3 discloses an image display device that alternately displays an image for the right eye and an image for the left eye, and thereby makes a stereoscopic image visually recognized. When there is a target region in which crosstalk occurs due to a large difference in luminance between an image for the right eye and an image for the left eye, the device in PTL 3 reduces influence of the crosstalk by making a tone correction to the target region and setting a gradation region around the target region.